Testing the Flux Rope Paradigm for Coronal Mass Ejections Using a Three Spacecraft Encounter Event

Abstract

We present a 3-D morphological and field reconstruction of a coronal mass ejection (CME) from 2023 November 28, which hits three spacecraft near 1 au: Wind at Earth's L1 Lagrange point; STEREO-A with a longitudinal separation of $6.5^{\circ}$ west of Earth; and Solar Orbiter (SolO) at $10.7^{\circ}$ east of Earth. The reconstruction assumes a magnetic flux rope (MFR) structure for the CME. With this event, we test whether field tracings observed by a spacecraft passing near the central axis of a CME MFR (STEREO-A) can be used to successfullly predict the field behavior seen by a spacecraft $17^{\circ}$ away (SolO), which has a more grazing encounter with the CME. We find that the MFR model does have significant success in simultaneously reproducing the field signs and rotations seen at STEREO-A, Wind, and SolO. This provides support for the MFR paradigm for CME structure. However, the SolO measurements, which are farthest from the central axis of the MFR, show less defined MFR signatures, presumably due to a greater degree of erosion and degradation of the MFR structure far from its central axis.